Automatic yarn feed rate control system for warp beam knitting machines

ABSTRACT

An automatic yarn feed rate control system for a warp beam knitting machine. The system comprises a digital pulse generator, a pulse multiplier, and a runner length multiplier coupled in series to the knitting machine crankshaft, for generating a digital pulse train, the number of pulses of which is proportional to the knitting machine knitting speed and the length of yarn consumed by the knitting machine during a predetermined knitting cycle. A plurality of interconnected counters adjusts the number of pulses of this pulse train to produce another pulse train, the number of pulses of which is inversely proportional to the instantaneous diameter of the knitting warp. The pulses of this latter pulse train are transmitted to a multivibrator and amplifier and drive a stepper motor which rotates the warp beam of the knitting machine at a speed which is inversely proportional to the warp diameter to maintain a constant yarn feed rate.

llnited States Patent Wilson et al.

Jan. 7, r975 AUTOMATIC YARN FEED RATE CONTROL Primary Examiner-Ronald Feldbaum SYSTEM FOR WARP BEAM KNITTING Attorney, Agent, or Firml(enyon & Kenyon Reilly MACHINES Carr & Chapin [75] Inventors: M. Van Wilson, Barboursville; Gary L. Miller, Gordonsville, both of Va. ABSTRACT [73] Assignee: Liberty Fabrics of New York, Inc., An automatic yarn feed rate controlsystem for a warp New York, NY, beam knitting machine. The system comprises a digital pulse generator, a pulse multiplier, and a runner [22] Flled' 1973 length multiplier coupled in series to the knitting ma- [21] Appl. No.: 423,124 chine crankshaft, for generating a digital pulse train. the number of pulses of which is proportional to the knitting machine knitting speed and thelength of yarn [52] US. Cl. 66/86 A, 66/125 R, 235/l5l.32 consumed by the knitting machine during a predeter- [51] Illl. Cl p041) 23/00 mined knitting cycle. A plurality of interconnected [58] Feld of Search 55/86 125 235/1513 counters adjusts the number of pulses of this pulse 235/5132 train to produce another pulse train, the number of pulses of which is inversely proportional to the instan- [56] References C'ted taneous diameter of the knitting warp. The pulses of UNI ED S ATES P T S this latter pulse train are transmitted to amultivibrator 3,668,904 6/1972 Murenbeeld 66/86 A and amplifier and drive a stepper motor which rotates 3,780,541 12/1973 Haynes 66/125 R the warp beam of the knitting machine at a speed 3,781,523 l2/l973 Dorsman 235/l5l.32 which is inversely proportional to the warp diameter to maintain a constant yarn feed rate.

10 Claims, 6 Drawing Figures Br I? 1% Fe i-R 1 B r (.56 MY swar Mme- Cwm e25- Za2 u l M6 '7 '8 Patented Jan. 7, 1975 3 Sheets-Sheet 1 HIT HF r WEZBO Patented Jan. 7, 1975 3 Sheets-Sheet 2 atent Jan. 7, 1975 3 Sheets-Sheet 5 NLUQ BACKGROUND OF THE INVENTION 1. Field Of The Invention The invention relates generally to knitting machines, and in particular, to a warp yarn feed rate control system for a warp beam knitting machine.

2. Description Of The Prior Art Warp beam knitting machines are known in the art, and gnerally speaking, the yarn used to knit a textile in such machines is first wound on one or more horizontally disposed elongated shafts called warp beams. The yarn is then advanced in parallel rows to a bank of knitting needles which oscillate rapidly in a gnerally vertical direction in response to movement of a crank shaft. Suitable drive means is provided for moving the needles through a predetermined knitting cycle, during which the knitting yarn is fed to the needles and interengaged therewith in accordance with a predetermined pattern. This interengagement is effected by means of one or more bars which guide the yarn from the warp beam and position the individual yarn strands for engagement with the knitting needles. The yarn strands are usually positioned by the bars while the needles are disposed in their vertically uppermost position. As the needles move downwardly, the knitting operation is carried out by means of a presser bar which weaves the yarn strands into the knitted fabric course by course. The guide bars of the machine generally move arcuately through the bank of needles, and longitudinally, the latter movements of which are timed in relation to the needle movement by a pattern control apparatus of the machine.

As yarn is drawn off a wrap beam during the knitting operation, the outside diameter of the warp, i.e., the yarn would on the warp beam, decreases, and the average rotational speed of the warp beam must be increased to maintain the yarn feed rate to the knitting needles constant. Failure to maintain a constant yarn feed rate and tension results in inferior textile fabrics knitted by the machine, which include such defects as visible lines, stop marks, and shade differences.

Yarn feed rate control systems for warp beam knitting machines are generally known in the art. See, for

example, US. Pat. Nos. 2,361,526; 2,470,125; 2,529,241; 2,539,295; 2,539,296; 2,600,256; 2,627,592; 2,664,724; 2,674,109; 2,707,380; 2,718,768; 2,719,419; 2,871,685; 2,910,850;

3,221,519; 3,364,403; and 3,470,921, which describe both electrical and electromechanical warp beam control systems for regulating the delivery speed of knitting machines. These systems are essentially closed loop servo-systems since they adjust the feed rate of the warp after determination of the knitting yarn demand of the machine, and have limited accuracy due to the time lag which exists between the determination of the yarn feed rate and the correction thereof with respect to yarn demand. Prior art systems also generally utilize rotatable followers which engage the warp to determine the yarn feed rate. These followers damage the yarn and ultimately reduce the quality of the knitted fabric. Total elimination of fabric defects thus cannot be attained with prior art devices.

SUMMARY OF THE INVENTION It is therefore an object of the invention to overcome the above-mentioned disadvantages of heretofore known feedrate control systems, and to provide an improved automatic yarn feed rate control system for warp beam knitting machines.

These and other objects are achieved in a warp beam knitting machine of thetype including knitting needles driven by a crankshaft, and drive means for feeding yarn from a warp wound on the warp beam to the knitting needles, by the provision of an automatic yarn feed rate control system which comprises a first -means which generates a first electrical signal which is proportional to both the knitting machine knitting speed and the length of yarn consumed by the knitting machine during a predetermined knitting cycle. The system further comprises second means, coupled to the first means and to the drive means, which generates a second electrical signal which is inversely proportional to the instantaneous diameter of the rotating warp. The second electrical signal drives the beam at a rotational speed dependent upon the diameter of the warp so that yarn is fed from the warp to the machine knitting needles at a constant feed rate as the warp diameter decreases.

In one embodiment of the invention, the first means comprises a pulse generator coupled to the knitting machine crankshaft which generates a pulse train, the number of pulses of which is proportional to the machine knitting speed, and a multiplier coupled to the pulse generator for multiplying the pulse train by the ratio of a predetermined maximum length of yarn and a desired length of yarn to be consumed by the knitting machine during the knitting cycle. The number of pulses of the pulse train is the reby adjusted so as to be additionally proportional to the desired length of yarn consumed during the knitting cycle. The second means of the system comprises a plurality of interconnected digital counters, the first of which counts a predetermined number of the pulses of the multiplier output and generates an output pulse each time the predetermined number count is reached. These output pulses comprise the second electrical signal generated by the second means. A second counter counts these output pulses and generates its own output signal after a predetermined number of first counter output pulses corresponding to a selected number of revolutions of the warp beam are counted. A third counter incrementally decreases the number of pulses counted by the first counter each time an output signal is generated by the second counter in order to adjust the yarn feed rate in accordance with the decreasing diameter of the warp.

BRIEF DESCRIPTION. OF THE DRAWINGS FIG. 1 is a schematic block diagram of an improved yarn feed rate control system for a warp beam knitting machine constructed according to the invention;

FIG. 2 is a partial schematic diagram of the control system of FIG. 1 showing its connection to the drive means and warp beam of the knitting machine;

FIG. 3 is a partial schematic diagram of the control system of FIG. 1 showing its connection to the knittin machine crankshaft;

FIG. 4 is an electrical schematic diagram of the pulse generator multiplier of the control system of FIG. 1;

FIG. 5 is an electrical schematic diagram of the pulse generator and amplifier of the control system of FIG. 1, showing its connection to the knitting machine crankshaft; and

FIG. 6 is an electrical schematic diagram of the runner length multiplier, pulse counters, and motor amplifier of the control system of FIG. 1.

DETAILED DESCRIPTION Referring now to the drawings, specifically FIG. 1, there is shown an automatic yarn feed rate control system constructed according to the invention. The system comprises a first means coupled to the knitting machine crankshaft (not shown) which comprises a pulse generator 10, a pulse multiplier 11, and a runner length multiplier 12. The pulse generator and multipliers in combination generate a first electrical signal, specifically a first pulse train comprising a plurality of successive digital pluses, the number of which is proportional to both the number of revolutions of the knitting machine crankshaft, i.e., the knitting speed, and the length of yarn consumed by the knitting machine, generally known as the runner length, during a predetermined knitting cycle, namely a rack or 480 stitches. Generally speaking, one stitch is equal to one crankshaft revolution. A second means, comprising first, second and third counters 13, 14 and 15, respectively, is coupled to the runner length multiplier and is responsive to the digital pulse train output thereof. The counters generate a second electrical signal comprising a second pulse train of successive digital pulses, the number of which is inversely proportional to the instantaneous diameter of the knitting machine warp (which comprises the yarn disposed on the warp beam). The second pulse train pulses are transmitted to a warp beam drive means which includes a one-shot multivibrator 16 which generates pulses of constant width in response thereto for driving a motor amplifier 17. A dc stepper motor 18 is coupled to the amplifier and is driven by the output pluses thereof.

As shown in FIGS. 2 and 3, warp beam 19 of the knitting machine is mounted on a warp shaft 20 which is coupled to stepper motor 18 by means of a chain and sprocket drive system. Knitting machine crankshaft 21 is coupled by a similar chain and sprocket drive system to pulse generator 10. For the purposes of clarity, only amplifier l7, multivibrator 16, pulse multiplier 11, and pulse generator of the system of FIG. 1 are illustrated in FIGS. 2 and 3. Pulse multiplier 11 is illustrated in detail in FIG. 4, and comprises a one-shot multivibrator 22, to which pluses generated by pulse generator 10 are trasmitted by means of multiplier input terminal 23. A flip flop 24, another one-shot multivibrator 25, and a shift register 26 are coupled in series to multivibrator 22. An oscillator 27 is coupled by means of two decade dividers 28 and 29 to flip flop 24 and a pair of inverters 30 and 31. The output terminal of inverter 30 is coupled to shift register 26 and to one input terminal of an AND logic gate 32, the other input terminal of which is coupled to the output terminal of shift register 26. The output terminal of inverter 31 is coupled to another shift register 33 and to one input terminal of another AND logic gate 34, the other input terminal of which is coupled to the output terminal of shift register 33. The output terminal of oscillator 27 is coupled by means of a third inverter 35 to a third shift register 36 and another AND logic gate 37. Shift register 36 has the input terminal thereof coupled to the output terminal of gate 34, and the output terminal thereof coupled to gate 37. The pulse signals generated by the multiplier are transmitted from gate 37 through multiplier output terminal 38 to runner length multiplier 12.

Pulse generator 10 is illustrated in detail in FIG. 5. As previously described, the knitting machine crankshaft 21 is coupled by means of a chain and sprocket drive system to the pulse generator, which comprises a shaft 39 on which a drive sprocket 40 is mounted. Sprocket gear 40 is coupled to shaft 21 by a chain and similar sprocket gear, and the gearing ratio can be chosen to suit the requirements of particular knitting machines. A rotating disc 41, having a plurality of circumferential, spaced apart slots 42 disposed between radially outwardly extending teeth 43, is mounted on the end of shaft 39 opposite sprocket gear 40. An incandescent or light emitting diode light source 44 is disposed behind disc 41 at the same radial position as the slots thereof so that the light beam transmitted by the light source along line 45 is interrupted as disc 41 rotates. A light sensitive photoelectric transistor 46 is disposed on the other side of disc 41 opposite light source 44 and is responsive to the light beam transmitted thereby. Light pulses generated by the disc and light source are converted to electrical pulse signals by transistor 46 and are amplified in a pulse amplifying and squaring circuit 47. The amplified electrical pulse signals are then transmitted to pluse multiplier 11 through pulse generator output terminal 48.

Runner length multiplier 12, counters 13, 14 and 15, and motor amplifier 17 are schematically illustrated in detail in FIG. 6. The runner length mulitplier comprises two serially connected integrated circuit rate multipliers'49 and having a plurality of switches 49a and 50a (12a in FIG. 1) coupled to the input terminals thereof. The rate multipliers are coupled to a plurality of serially connected down counting decade counters DCl through DC4 which comprise part of counter 13. The output terminal of each of the decade counters is coupled to a corresponding input terminal of an AND logic gate 51. Anne-shot multivibrator 52 is coupled to the output terminal of the gate for generating pulses of constant width in response to the output of gate 51. The output terminal of multivibrator 52 is coupled both to multivibrator l6 and to the reset terminal of each of the decade counters. Counter 14 comprises another series of down counting decade counters DCS through DC8, the output terminals of which are coupled to the decade counters of counter 13. A plurality of switches 53 and 54 are coupled to the input terminals of decade counters DCS-DC8 for setting the initial count of both counters 13 and 14. Counter 15 is coupled to the output terminal of multivibrator l6 and also comprises a plurality of serially connected down counting decade counters DC9 through DC13. Another AND logic gate 55 is coupled to the output terminals of decade counters DC9 DC12, and drives a one-shot multivibrator 56 coupled to the output terminal thereof. One output terminal of the multivibrator is coupled to the reset terminals of decade counters DC9-DC13; the other terminal is coupled to the input terminal of decade counter DC5 of counter 14. Switches 57 and 58 (15a in FIG. 1) are coupled to the input terminals of decade counters DC9 to DC12 for setting the count (which corresponds to the number of pulses associated with a desired increment of rotation of the warp beam) of counter 15. The

operation of the above described illustrated embodiment of the invention is as follows:

The basic parameters of the warp feed control are the warp diameter, the warp yarn length (yardage), the number of warp beam revolutions required to make up the yarn warp, and the desired feed rate per rack. These quantities are determined by measurement. Assume for the purpose of the following explanation that the warp is wound under constant tension control and at the specified runner length tension. As described previously, runner is the length of yarn consumed by the knitting machine (unwound from the warp beam) in knitting one rack or 480 stitches. The warp diameter is determined as follows:

TOTAL YARDS X 36 INCHES TOTAL INCHES TOTAL INCHES 25.40005 TOTAL MILLIMETERS TOTAL MILLIMETERS OF YARN NUMBER OF REVOLUTIONS OF WARP AVERAGE CIRCUMFERENCE And,

AVERAGE CIRCUMFERENCE 2 AVERAGE WARP DIAMETER (D average) 1r From the last equation it can be derived that D average O.D. I.D./2

2 X D average 150 mm. O.D. mm.,

and

0.03937 inch/mm. X O.D. mm. 0.0. inches.

Then, total yarn length equals (0.0. I.D.)/2 (1r) (TOTAL NUMBER OF REVOLUTIONS) Once the warp diameter has been determined, the thickness of each revolution is determined by (O.D. I.D.)/TOTAL NUMBER OF REVOLUTIONS The value t represents the decrease in the warp diame ter after each revolution of the warp an is constant during consumption of the warp yarn. The warp diameter D,, after any number of warp revolutions it during the yarn consumption is described by the equation:

where D, is the initial diameter of yarn on the warp and R, represents the number of turns unwrapped from this initial diameter. To provide a desired runner length at,

any time during yarn consumption, the warp must rotate at a rate described by the following equation:

WARP ROTATION/RACK RUNNER LENGTH/11D RUNNER LENGTH/(D, tR,,)1r

This equation is of the general form of a hyperbola,

specifically a rectangular or equilateral hyperbola,

whose asymptotes are perpendicular and form the co ordinate axes. This hyperbola represents the required yarn feed rate in terms of revolutions of the warp per rack for a desired beam feed from a warp of given diameter during a predetermined number of revolutions. Thus, the yarn feed rate is equal to the beam feed divided by the circumference of the warp.

For the purposes of the explanation herein, it will be assumed that the warp is formed by three warps of knitting yarn about the beam for each millimeter of spool diameter. The typical spool previously described has a diameter of 150mm when empty, and a diameter of 508mm when fully wrapped. There are, thus 358mm of usable diameter for each warp beam, and, since there are three wraps of yarn for each mm of diameter, the total number of revolutions for such a warp would be 1074. Since each revolution of the warp unwinds one thickness of yarn from the warp beam, the circumference of the warp is decreased by m. It is thus evident that the yarn feed rate changes after each revolution of the warp, and is properly represented by the function I K/X. Since the yarn feed rate represents the number of warp revolutions per rack, it is also representa tive of the required gearing ratio between the knitting machinecrankshaft and the warp beam drive shaft which must be chosen to produce the required warp feed rate per rack. Thus, as the warp diameter decreases after each revolution, the rate at which the warp beam shaft must be driven to maintain a given feed rate changes, and the gearing ratio between the crankshaft and the warp beam drive shaft must be adjusted. The automatic control system of the invention accurately adjusts the gearing ratio to compensate for the decreasing diameter of the warp and maintain a constant yarn feed rate into the knitting machine.

In the illustrated embodiment of the invention, disc 41 of pulse generator 10 generates, as previously described, a plurality of successive digital light pulses in response to rotation of knitting machine crankshaft 21 by interrupting the light beam emitted by source 44. The gearing ratio between the crankshaft and the disc drive shaft may be chosen as desired; the simplest ratio is 1:], since in that case the number of pulses generated equals the number of disc slots. These pulses are transmitted to pulse multiplier 11 which greatly increases the number of pulses generated for each crankshaft revolution. The number of pulses generated for each crankshaft revolution. The output pulses of the pulse multiplier are the control signals for stepper motor 18. A specified number of signals are required to turn the motor shaft through one revolution, and, depending upon the gearing ratio between the warp beam shaft and the motor, the number of pulses required to turn the warp through one revolution will be greater or less than this specified number. If the gearing ratio, for example, is 25:] between the motor and warp beam shafts, and 200 pulses are required to rotate the motor shaft through one revolution, 5,000 pulses will be required to rotate the warp through one revolution. If the desired yarn feed rate is one revolution of warp per rack, the 5,000 pulses must be generated during one rack of machine operation (480 revolutions of crankshaft 21). In the illustrated embodiment of the invention, pulse multiplier 11 multiplies the input from generator 10 so that each pulse in produces 512 pulses out. If disc 41 contains, for example, slots, pulses will be supplied to the stepper motor at a rate of 40,960 pulses per revolution thereof. Since one rack of machine operation is 480 crankshaft revolutions, the pulses supplied to the stepper motor by multiplier 11 will be 19, 660, 800 per rack. This pulse rate is directly proportional to the knitting machine knitting speed. The parameters of pulse generator 10 and multiplier 11 control this pulse rate and are chosen so that if runner length multiplier 12 is set to multiply by the factor 1.000, its maximum multiplication factor, the pulse train output of multiplier 12 is at a rate which corresponds to that required to feed a maximum runner length that is required, for example, 150 inches of yarn, from the warp to the knitting needles. Runner lengths are dictated by the fabric pattern or style knitted on the machine and are varied accordingly. Thus, if the style or pattern knitted requires a 75 inch runner per rack, runner length multiplier 12 is set by means of switches 49a and 50a to multiply the output of multiplier 11 by the ratio of the desired to maximum runner length, which in this example would be 75/150 or 0.500. The pulse train generatedby multiplier 11 is thus reduced from 19,660,800 pulses to 9,830,400 pulses per rack.

Assuming that a 75 inch runner length is desired, and that the diameter of the warp is inches at some point in'time during the knitting of the corresponding rack, the circumference of the warp at this point in time is 20w or 62.832 inches. The knitting of one rack thus requires a warp rotation of 75 inches/62.832 inches, or 1.1937 revolutions per rack. Since the gearing ratio between motor 18 and the warp beam requires 5,000 pulses to step motor 18 through one warp beam revolution, 5968.5 input pulses are required per rack to drive the warp through 1.1937 revolutions. Counter 13 is set to count a predetermined number of pulses and then generate an output pulse to drive motor 18. The action of counter 13 is merely to generate one pulse out in response to a specific number of pulses received. This in effect multiplies the incoming pulses by a specific factor which is inversely proportional to a selected diameter of thewarp. 1n the described example, the factor is 1/5968.65, and the pulse output of counter 13 is 9,830, 400 multiplied by 1/5968.5 or 1,647. Thus, when counter 13 is set to a count of 1,647, and downcounts in response to the output of runner length multiplier 12, one output pulse is generated by counter 13 for every 1,647 pulses supplied by runner length multiplier 12.

The initial set count for counter 13 is, however, correct only when the diameter of the warp is 20 inches. As the fabric is knitted and the yarn consumed, the warp diameter diminishes and the count set of counter l3must also be diminished. This is accomplished by means for adjusting the magnitude of this multiplication factor as a direct function of the instantaneous warp diameter, illustrated as counters l4 and 15. Assuming that the 20 inch diameter warp described has three turns of yarn for each millimeter of yarn diameter, and that the empty warp beam diameter is 150mm,

the warp diameter is (20.000) (25.4) 150mm tion or number of revolutions which reduces the diameter by an amount proportional to a one digit reduction in the multiplication factor set count, to ensure that the set count accurately represents the instantaneous warp diameter. This is determined as follows:

and

Thus, each time the diameter of the warp decreases by 0.01214 inches, the set count of counter 13 must be reduced one digit. This diameter increment is equiva lent to 0.92508 revolutions of the warp. (0.92508) (5000)= 4625 pulses are required to drive the warp through this much rotation. The counter 15 is thus set by switches 15a to this set count (4625) and downcounts to zero the pulses generated by counter 13. When counter 15 reaches zero (signifying that the warp diameter has decreased by 0.01214 inches) it generates an output pulse which both resets counter 15 to the set count and reduces the set count of counter 14, and thus counter 13, by one digit. (1n the embodiment of the invention illustrated, the set count. of counter 13 is set through counter 14 by means of switches 14a.) Thus, assuming operation is initiated with a warp having a 20.000 inch diameter and a set count of 1647, after rotation ofthe warp through 0.92508 revolutions, and the counting of 4625 pulses by the counter 15, the set count of counter 14 is reduced to smaller set count then becomes the multiplication factor for counter 13, with the result that the output of the runner length multiplier and the rotational speed of the warp are increased to compensate for the decreased warp diameter and maintain the yarn feed rate constant.

As previously stated, pulse multiplier 11 generates 512 pulses for each one generated by pulse generator 10. To carry out this multiplication, the input pulses are transmitted by means of input terminal 23 to one-shot multivibrator 22 which generates a pulse of constant width which clears flip flop 24. Oscillator 27 operates at a specified frequency, approximately 1.5 MHZ, and its output is divided twice by decade dividers 29 and 28 to provide a synchronizing pulse train of approximately 15,000 pulses/sec. at the set terminal of flip flop 24.

.After each pulse generated by one-shot 22 clears flip flop 24, the next synchronizing pulse from oscillator 27 sets the flip flop and causes an output signal to be transmitted to multivibrator'25. Multivibrator 25 functions as a trigger and generates one pulse for each input pulse to the multiplier which is shifted in time so as to be synchronized with the pulse train generated by oscillator 27. The pulsesproduced by multivibrator 25 load an eight-bit shift register 26, which has the eight input data lines thereof (schematically represented by terminal 26a) set for continuous all ones data. The load pulses cause the data lines to parallel load all eight bits of the shift register to all ones, and the synchronizing pulses generated by oscillator 27 are transmitted through decade dividers 28 and 29, and inverter 30, to shift the register so hat eight serial ones are produced at the output of register 26 in synchronism with the-synchronizing pulses. These ones are reduced in width an AND gate 32 to match the synchronizing pulse width. A train of pulses eight times greater than 1646. This newthe input pulses is thus produced at the output of gate 32 The pulses at gate 32 are then transmitted to another 8 bit shift register 33 and load the register with ones" data. The data input terminals 33a of the register are set for continuous all ones data. The shift command signal for register 33 is transmitted from oscillator 27 to divider 28 and inverter 31, and has a pulse repetition frequency which is times greater than that used to shift register 26. The serial pulse output of register 33 is transmitted to AND gate 34, to which the same synchronizing pulses are transmitted, and eight pulses are produced at the output of gate 34 for each pulse transmitted by AND gate 32. At this stage of the multiplication operation, the input pulses have been multiplied by the integer 64.

The above described multiplication operation is repeated again in another eight bit shift register 36. This register has input terminals 36a set for all ones" data and is parallel loaded with all ones by the output pulses of gate 34. The shift command signal for register 36 is transmitted from oscillator 27 through inverter 35 and is 10 times greater than that used to shift register 33. AND gate 37 is coupled to the outputs of register 36 and inverter 35, and produces the total number of pulses which are to be transmitted to runner multiplier 12. At this final stage of multiplication, the input pulses have been multiplied three times by the integer 8, and 512 output pulses are generated by multiplier 11 for each input pulse transmitted thereto.

Output pulses are transmitted from multiplier 11 to runner length multiplier 12, which multiplies the pulses by a fraction between 0.000 to 1.00 chosen as previously described. The output pulses of multiplier 12 are proportional in number to both the number of crankshaft revolutions and the runner length consumed during the knitting of one rack, and are ready to be reduced to the number required for driving the warp beam at the desired feed rate. As previously described, this is carried out by decade counters DCl through DC4, gate 51 and multivibrator 52. Counter 13 is loaded by means of switches 53 and 54 of counter 14 to the set count representing the diameter of the warp used. In the described embodiment of the invention,

counter 13 is set to the digit 1647 through the parallel when all the counters reach the digit 0,.output signals are simultaneously transmitted therefrom to gate 51 whose output signal activates multivibrator 52. The pulse generated by the latter is transmitted both to multivibrator 16 and to the reset terminals of decade counters DCl through DC4. The output pulses thus reset the decade counters and drive the stepper motor.

The ouput of one-shot 16 is also transmitted to decade counter DC13 of counter which counts the warp beam turns by counting the number of pulses generated by the one-shot during a specified amount of warp beam revolution. In the inllustrated embodiment of the invention, 4625 steps of the motor are required to rotate the warp beam through 0.92508 revolutions. Switches 57 and 58 (15a in FIG. 1) of counters DC9 through DC12 are thus set to downcount one digit at a time from 4625 through each incremental warp diameter decrease. This set count is set in the switches in binary coded decimal form. When the decade counters downcount to zero, an output pulse is generated at AND gate 55 which activates mlultivibrator 56. The pulse generated by multivibrator 56 both resets each of v the decade counters DC9 through DC13 and causes warp, the number of wraps and length of yarn required to make a warp of given dimensions should be noted and recorded. If a warp wound on; a beam of given dimensions has a diameter when fully wrapped which is less than the maximum possible diamter, a proprotionate number of digits is merely subtracted from the maximum diameter starting number and set in counter 13. Also, if the turns per diameter factor is greater or less than the 0.92508 revolutions per increment calculated herein, the counter 15 is merely set to a higher or lower number to count more or less pulses (and thus warp revolutions). This is typical of various warps made of various denier or thickness of yarns.

In the foregoing the invention has been described with reference to specific exemplary embodiments thereof. It will be evident, however, that variations and modifications may be made thereunto without departing from the broader scope and spirit of the invention as set forth in the appended claims. The specification and drawing are accordingly to be regarded in an illustrative rather than in a restrictive :sense.

What is claimed is:

1. In a warp beam knitting machine of the type including knitting needles driven by a crankshaft, and drive means for feeding yarn from a warp wound on the warp beam to the knitting needles, an automatic yarn feed rate control system comprising:

first means for generating a first electrical signal which is proportional to both the knitting speed of the knitting machine and the length of yarn consumed by the knitting machine during'a predetermined knitting cycle; and

second, means, coupled to said first means and to said drive means, for generating a second electrical sig nal which is inversely proportional to the instantaneous diameter of the warp, said second electrical signal driving the warp beam at a rotational speed dependent upon the diameter of the warp so that yarn is fed fromsaid warp to said knitting needles at a constant feed rate.

2. The control system recited in claim 11, wherein said first means comprises signal generating means coupled to said crankshaft for generating an electrical signal which is' directly proportional to the knitting speed of the knitting machine, and means, coupled to said signal generating means, for multiplying said electrical signal generated thereby by the ratio of a desired length of yarn and a predetermined maximum length of yarn to be consumed by the knitting machine during said knitting cycle.

3. The control system recited in claim 1, wherein said first means comprises a pulse generator coupled to said crankshaft for generating a pulse train, the number of pulses of said pulse train generated during said knitting cycle being proportional to the knitting machine knitting speed, and a first multiplier, coupled to said pulse generator, for multiplying said pulse train by the ratio of a desired length of yarn and a predetermined maximum length of yarn to be consumed by the knitting machine during said knitting cycle, and thereby adjusting the number of pulses of said pulse train so that said number of pulses thereof is additionally proportional to said desired length of yarn consumed during said knitting cycle.

4. The control system recited in claim 3, wherein said first means further comprises a second multiplier, coupled to said pulse generator and to said first multiplier, for increasing in number the total number of pulses generated by said pulse generator during said knitting cycle.

5. The control system recited in claim 3, wherein said pulse generator comprises a rotatable disc coupled to said knitting machine crankshaft, having a plurality of spaced apart circumferential slots disposed on the periphery thereof, a light source disposed adjacent said disc on one side thereof, and photoelectric detection means, disposed on the other side of said disc opposite said light source, for detecting light pulses generated by said disc.

6. The control system recited in claim 1, wherein said second means comprises means, coupled to said first means, for multiplying said first electrical signal by a factor which is inversely proportional to a selected diameter of the warp, and means, coupled to said multiplying means, for adjusting the magnitude of said factor as a direct function of the instantaneous warp diameter.

7. The control system recited in claim 1, wherein said first electrical signal comprises a first pulse train, the number of pulses of which is proportional to said machine speed and length of yarn consumed, and said second electrical signal comprises a second pulse train, the number of pulses of which is inversely proportional to the instantaneous warp diameter; and wherein said second means comprises a first counter, coupled to said first means, for counting in succession a predetermined number of said first pulse train pulses and generating in response hereto one pulse of said second pulse train each time said number of first pulse train pulses is counted;

a second counter, coupled to said first counter, for

counting said second pulse train pulses and generating an output signal after a predetermined number of said second pulse train pulses corresponding to a selected number of revolutions of said warp beam are counted; and

a third counter, coupled to said first and second counters, for incrementally decreasing by a predetermined amount said number of first pulse train pulses counted by said first counter each time an output signal is generated by said second counter.

8. The control system recited in claim 7, wherein said first counter comprises a plurality of serially connected downcounting decade counters, AND logic gate means coupled to said decade counters, and a multivibrator coupled to said gate means.

9.'The control system recited in claim 8, wherein said second counter comprises a plurality of serially connected down-counting decade counters, coupled to said first counter, AND logic gate means coupled to said second counter decade counters, and a multivibrator coupled to said second counter gate means.

10. The control system recited in claim 9, wherein said third counter comprises a plurality of serially connected downcounting decade counters, coupled to said second counter multivibrator and said first counter de- UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Dated J nuary 7, 975

Patent No. 3,858, -Ll5 Column 12,

(SEAL) Attest:

RUTH C. MASON- Attesting Officer Signed and sealed change change change change change change lnventofls) M. Van {Wilson and Gary L. Miller It is certified that error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

"gnerally" to generally 5 "trasmitted" to transmitted "an" to and 3 "hat" to that 3 "diamter" to diameter 3 "hereto" to thereto this 18th day of March 1975.

D'IARSHALL DANN Commissioner of Patents and Trademarks ORM PC3-1050 (10-69) USCOMMI-DC 60376-P69 v: u.s. GOVERNMENT PRINTING orncs I969 0-366-384, 

1. In a warp beam knitting machine of the type including knitting needles driven by a crankshaft, and drive means for feeding yarn from a warp wound on the warp beam to the knitting needles, an automatic yarn feed rate control system comprising: first means for generating a first electrical signal which is proportional to both the knitting speed of the knitting machine and the length of yarn consumed by the knitting machine during a predetermined knitting cycle; and second means, coupled to said first means and to said drive means, for generating a second electrical signal which is inversely proportional to the instantaneous diameter of the warp, said second electrical signal driving the warp beam at a rotational speed dependent upon the diameter of the warp so that yarn is fed from said warp to said knitting needles at a constant feed rate.
 2. The control system recited in claim 1, wherein said first means comprises signal generating means coupled to said crankshaft for generating an electrical signal which is directly proportional to the knitting speed of the knitting machine, and means, coupled to said signal generating means, for multiplying said electrical signal generated thereby by the ratio of a desired length of yarn and a predetermined maximum length of yarn to be consumed by the knitting machine during said knitting cycle.
 3. The control system recited in claim 1, wherein said first means comprises a pulse generator coupled to said crankshaft for generating a pulse train, the number of pulses of said pulse train generated during said kNitting cycle being proportional to the knitting machine knitting speed, and a first multiplier, coupled to said pulse generator, for multiplying said pulse train by the ratio of a desired length of yarn and a predetermined maximum length of yarn to be consumed by the knitting machine during said knitting cycle, and thereby adjusting the number of pulses of said pulse train so that said number of pulses thereof is additionally proportional to said desired length of yarn consumed during said knitting cycle.
 4. The control system recited in claim 3, wherein said first means further comprises a second multiplier, coupled to said pulse generator and to said first multiplier, for increasing in number the total number of pulses generated by said pulse generator during said knitting cycle.
 5. The control system recited in claim 3, wherein said pulse generator comprises a rotatable disc coupled to said knitting machine crankshaft, having a plurality of spaced apart circumferential slots disposed on the periphery thereof, a light source disposed adjacent said disc on one side thereof, and photoelectric detection means, disposed on the other side of said disc opposite said light source, for detecting light pulses generated by said disc.
 6. The control system recited in claim 1, wherein said second means comprises means, coupled to said first means, for multiplying said first electrical signal by a factor which is inversely proportional to a selected diameter of the warp, and means, coupled to said multiplying means, for adjusting the magnitude of said factor as a direct function of the instantaneous warp diameter.
 7. The control system recited in claim 1, wherein said first electrical signal comprises a first pulse train, the number of pulses of which is proportional to said machine speed and length of yarn consumed, and said second electrical signal comprises a second pulse train, the number of pulses of which is inversely proportional to the instantaneous warp diameter; and wherein said second means comprises a first counter, coupled to said first means, for counting in succession a predetermined number of said first pulse train pulses and generating in response hereto one pulse of said second pulse train each time said number of first pulse train pulses is counted; a second counter, coupled to said first counter, for counting said second pulse train pulses and generating an output signal after a predetermined number of said second pulse train pulses corresponding to a selected number of revolutions of said warp beam are counted; and a third counter, coupled to said first and second counters, for incrementally decreasing by a predetermined amount said number of first pulse train pulses counted by said first counter each time an output signal is generated by said second counter.
 8. The control system recited in claim 7, wherein said first counter comprises a plurality of serially connected downcounting decade counters, AND logic gate means coupled to said decade counters, and a multivibrator coupled to said gate means.
 9. The control system recited in claim 8, wherein said second counter comprises a plurality of serially connected down-counting decade counters, coupled to said first counter, AND logic gate means coupled to said second counter decade counters, and a multivibrator coupled to said second counter gate means.
 10. The control system recited in claim 9, wherein said third counter comprises a plurality of serially connected downcounting decade counters, coupled to said second counter multivibrator and said first counter decade counters. 